This invention relates to cooling systems, and more particularly, to cooling systems for utilization on vehicles where plural, different heat exchange fluids require cooling.
So-called xe2x80x9ccompact cooling systemsxe2x80x9d, especially for vehicular applications, are being investigated at an ever increasing rate. Typically, they have several heat exchangers which are positioned to define a housing. Within the housing thus defined is the impeller of a radial fan. The front of the housing is closed but includes an inlet nozzle facing the impeller and the rear wall of the housing is also closed. The impeller draws fresh air into the housing through the nozzle and expels the same radially outwardly, as cooling air, through each of the heat exchangers. Typically, the rear wall of the unit provides a journal for the impeller. Certain of the heat exchangers may be devoted to cooling the coolant of an internal combustion engine while another may be utilized to cool combustion air from the engine after it has had its pressure increased by a turbocharger or the like. Still another may be utilized as a condenser or gas cooler in an air conditioning system for the vehicle and still another may be utilized as an oil cooler for oil in vehicular systems that requires cooling, particularly, transmission oil.
One example of such an apparatus is described in European Patent Application No. 9910760.9, the entire disclosure of which is herein incorporated by reference.
Other apparatus with some similar features are also shown in U.S. Pat. No. 4,202,296 and German Patent 3148942C2. The apparatus of the two identified patents do not relate to casing-like configurations as alluded to above wherein several individual cooling units are employed. Rather, they relate to so-called xe2x80x9cring-typexe2x80x9d cooling units which are more expensive to produce and consequently have not seen wide spread use as of the present. In the case of both, radial fans rotatable about a vertical axis have been employed but such a position is not particularly advantageous in terms of the efficiency of the fan.
Still another example of a ring-type cooling unit is shown in German Patent DE AS2716997 which does have the advantage of cooling several different cooling mediums. However, the cost of manufacturing a cooling system according to this patent is quite expensive.
Radial fans used in these type of apparatus, in which the ratio of the diameter of the inlet nozzle to the diameter of the impeller lies approximately between 0.6 and 0.9, are relatively quiet and have a compact design. See, for example, the text xe2x80x9cVentilatorsxe2x80x9d, 5th Edition, 1972, page 151 by Dr. Bruno Eck. Radial fans are, of course, also subject to other operational parameters. For example, a certain optimal width of the impeller can be coordinated with a certain diameter of the inlet nozzle. During the operation of radial fans, so-called xe2x80x9caperture flowxe2x80x9d occurs between the nozzle and the cover plate of the impeller. The magnitude of such flow is dependent upon the formation of the aperture or in-flow nozzle and may have the result that an area of lower pressure is formed in the area of the cover plate for the impeller. This encourages flow from areas of higher pressure and reduces performance, particularly if air is drawn as a back flow through one or more of the heat exchangers.
The present invention, then, is intended to provide an improvement in cooling apparatus of the foregoing type insofar as the efficiency of the apparatus is concerned.
It is the principal object of the invention to provide a new and improved cooling system, particularly for a vehicle. More particularly, it is an object of the invention to provide a so-called compact cooling system wherein a plurality of heat exchangers are arranged to create a housing in which a radial fan is disposed and losses due to aperture flow and other inefficiencies are minimized or avoided altogether.
An exemplary embodiment of the invention achieves the foregoing object in a cooling system that includes a plurality of at least three heat exchangers, each having two headers, and in proximity to each other. The heat exchangers are positioned to define a housing in the form of a polygonal solid and with the headers of one heat exchanger being in substantial abutment with the respective header of two different, adjacent heat exchangers. At least one of the heat exchangers is adapted to receive a first heat exchange fluid different from a second heat exchange fluid that is received by at least one of the other heat exchangers. A radial fan rotatable about an axis and having an impeller disposed within the housing as provided. The impeller includes blades for flowing air generally radially outward through the heat exchangers. A front panel is located on the housing and includes an inlet nozzle coaxial with the axis and focused on the impeller. A rear panel is also located on the housing and a shaft extends rearwardly from the rear panel along the axis and is coupled to the impeller. A journal for at least one of the impeller and the shaft to provide the desired rotation about the axis is provided. The system is characterized by the fact that the center line of the radially outer part of the blades taken in a plane transverse to the rotational axis is located between the front panel and the center line of the housing. It is further characterized by the ratio of the distance from the front panel to the center line of the blades to the diameter of the impeller at the radially outer part of the blades being in the range of about 0.20 to about 0.36.
In a preferred embodiment, at least two of the heat exchangers are radiators and the first fluid is a coolant for an internal combustion engine.
A preferred embodiment of the invention also contemplates that one of the heat exchangers is a charge air cooler and the second fluid is combustion air for an internal combustion engine.
According to one embodiment of the invention one of the heat exchangers is a gas cooler and the second fluid is a refrigerant for an air conditioning system.
Still another embodiment of the invention contemplates that one of the heat exchangers is an oil cooler and the second fluid is oil.
In a highly preferred embodiment, the ratio is in the range of about 0.25 to about 0.32.
In a highly preferred embodiment, the blades curve rearwardly in the direction of rotation of the impeller.
A preferred embodiment of the invention contemplates that the rear panel has a number of corners equal to the number of heat exchangers and a plurality of support struts, each extending from a respective one of the corners towards the axis. Connection plates are located at each of the corners and at least one fluid port is located in at least two of the connection plates. Flow channels, including a fluid inlet and a fluid outlet, are connected to the fluid ports.
In one embodiment, the flow channels are mounted on the rear panel.
A preferred embodiment also contemplates that the rear panel have a central convex section centered about the axis and extending inwardly into the housing.
Other objects and advantages will become apparent from the following specification taken in connection with the accompanying drawings.